Make all blending up to GrOptDrawState be handled by the xp/xp factory.

src/gpu/GrProcOptInfo.cpp

Index: src/gpu/GrProcOptInfo.cpp
diff --git a/src/gpu/GrProcOptInfo.cpp b/src/gpu/GrProcOptInfo.cpp
index 18a32020d4539154ca9d993ea98698ea05f3c35f..a84ac2e17fb45dcfb2a9f556b2a628dd68bcf53f 100644
--- a/src/gpu/GrProcOptInfo.cpp
+++ b/src/gpu/GrProcOptInfo.cpp
@@ -7,8 +7,9 @@
 
 #include "GrProcOptInfo.h"
 
-#include "GrGeometryProcessor.h"
+#include "GrFragmentProcessor.h"
 #include "GrFragmentStage.h"
+#include "GrGeometryProcessor.h"
 
 void GrProcOptInfo::calcWithInitialValues(const GrFragmentStage* stages,
                                           int stageCount,
@@ -22,6 +23,7 @@ void GrProcOptInfo::calcWithInitialValues(const GrFragmentStage* stages,
     fInputColor = startColor;
     fRemoveVertexAttrib = false;
     fReadsDst = false;
+    fReadsFragPosition = false;
 
     if (areCoverageStages && gp) {
         gp->computeInvariantOutput(&fInOut);
@@ -31,17 +33,22 @@ void GrProcOptInfo::calcWithInitialValues(const GrFragmentStage* stages,
         const GrFragmentProcessor* processor = stages[i].getProcessor();
         fInOut.resetWillUseInputColor();
         processor->computeInvariantOutput(&fInOut);
-        #ifdef SK_DEBUG
+#ifdef SK_DEBUG
         fInOut.validate();
-        #endif
+#endif
         if (!fInOut.willUseInputColor()) {
             fFirstEffectStageIndex = i;
             fInputColorIsUsed = false;
-            fReadsDst = false; // Reset this since we don't care if previous stages read dst
+            // Reset these since we don't care if previous stages read these values
+            fReadsDst = false;
+            fReadsFragPosition = false;
         }
         if (processor->willReadDstColor()) {
             fReadsDst = true;
         }
+        if (processor->willReadFragmentPosition()) {
+            fReadsFragPosition = true;
+        }
         if (kRGBA_GrColorComponentFlags == fInOut.validFlags()) {
             fFirstEffectStageIndex = i + 1;
             fInputColor = fInOut.color();
@@ -50,7 +57,10 @@ void GrProcOptInfo::calcWithInitialValues(const GrFragmentStage* stages,
             // Since we are clearing all previous color stages we are in a state where we have found
             // zero stages that don't multiply the inputColor.
             fInOut.resetNonMulStageFound();
-            fReadsDst = false; // Reset this since we don't care if previous stages read dst
+            // Reset these since we don't care if previous stages read these values
+            fReadsDst = false;
+            fReadsFragPosition = false;
         }
     }
 }
+